1. Field of the Invention
The present invention relates in general to an artificial lighting apparatus using light emitting diodes as a light source for young plants, especially plantlets growing in tissue culture vessels. During the lightperiod provided to the plant, the light quantity, light quality, duty ratio and frequency of the mixed light source of the present invention are adjustable.
2. Description of the Related Art
In the past, tubular fluorescent lamps (TFLs) were used as artificial light sources in plant tissue culture. However, TFL has problems including heat generation, easy decay, fixed light quality, short life span and flickering. Light emitting diodes (LEDs) have no excess heat problem; thus, LEDs can be arranged very close to the cultured plant to save space. In addition, LEDs have the advantages of a long life span and low power consumption. Therefore, research in culturing plants with LEDs has been proceeding. In 1992, Hoenecke, et al. successfully cultured vegetables by using high intensity red LEDs (Hoenecke, M. E., R. J. Bula, and T. W. Tibbitts, 1992, Importance of xe2x80x98Bluexe2x80x99 photon levels for lettuce seedlings grown under red-light-emitting diodes, HortScience 27(5):427-430). In 1993, blue LEDs were successfully developed. In 1996, Okamoto et al. used high intensity red LEDs and blue LEDs to culture plants, with the quantum ratio of 2:1 for red light/blue light (Okamoto, K., T. Yanagi and S. Takita, 1996, Development of plant growth apparatus using blue and red LED as artificial light source, Acta Hort., 440:111-116). Also in 1996, Yanagi et al. used blue LEDs (170 xcexcmol/m2/s) to culture lettuce (Yanagi, T., K. Okamoto and S. Takita, 1996, Effects of blue, red and blue/red lights of two different PPF levels on growth and morphogenesis of lettuce plants, Acta Hort, 440:117-122). The dry weight of the cultured lettuce using pure blue light was less than that of the lettuce cultured by pure red light or red/blue light. Nevertheless, the cultured lettuce was short and healthy.
All prior research was made on a small scale, while the present invention is provided for the purpose of mass production. The present invention provides a plant-growing bench including at least one electric track and a plurality of lamps. The lamps, referred to as LEDsets, are detachably mounted on the electric track. Each of the LEDset includes a mounting box and at least one type of light emitting diode mounted on the box. The electric track supplies the LEDsets with power to light the diodes.